JPH05282775A - Digital signal reproducing device - Google Patents

Abstract

PURPOSE:To obtain a continued reproduced signal in which any part of the signal is never lacked in spite of vibration of a device, in a digital signal reproducing device which reproduces a digital signal recorded in a recording medium. CONSTITUTION:When a digital signal from a reproducing section 9 is stored in a buffer memory 17 by a specified volume temporarily, a control section 8 outputs the digital signal from the buffer memory 17 with a constant transfer rate corresponding to normal driving speed of a recording medium 10. During specified volume of the digital signal is stored in the buffer memory 17, the recording medium 10 is driven with a normal driving speed, let a signal detecting section 13 move to a position before vibration of the recording medium 10 is detected in accordance with a vibration detecting signal from a vibration detecting section 14. A driving section 12 and the reproducing section 9 reproduces the signal with a driving speed of the recording medium 10 higher than a normal driving speed until the digital signal stored in the buffer memory 17 becomes the specified volume.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital signal reproducing device, and more particularly to a digital signal reproducing device for reproducing a digital signal recorded on a recording medium by relatively moving a signal detector and a recording medium.

[0002]

2. Description of the Related Art FIG. 5 is a block diagram of an example of a CD (Compact Disc) player which is a conventional digital signal reproducing apparatus.

In FIG. 5, a microprocessor 1 controls a signal detector 13, a servo circuit 4, a signal processor 5, and the like.

The signal detection unit 13 is an optical pickup, and the drive unit 2 is composed of a feed motor for controlling the optical pickup 13, a two-dimensional actuator, a spindle motor for driving the optical disc 10 as a recording medium, and the like.

The drive unit 2 is driven by a signal from the servo circuit 4 so that the optical pickup 13 tracks the track of the optical disc 10, and a digital audio signal (hereinafter, referred to as "recorded on the optical disc 10" as a current signal from the optical pickup 13 will be described. A digital signal or data) is detected for simplicity.

This digital signal is current-voltage converted and RF-amplified by the RF amplifier circuit 3, and is supplied to the servo circuit 4 and the signal processor 5.
The servo circuit 4 generates signals such as a tracking error signal, a focus error signal, and a spindle motor drive signal.

The RF-amplified reproduced digital signal supplied to the signal processor 5 is converted into 8-12 bits according to the format of the CD data, and after being subjected to processing such as decoding and error processing, The analog audio signal is converted by the D / A converter 6. The analog audio signal is amplified by the audio signal amplifier circuit 7 and output.

[0008]

However, the above-mentioned C
In the D player, when the device vibrates due to an external cause and the optical disc vibrates with respect to the optical pickup, for example, the focus of the optical pickup shifts and a digital signal having a predetermined amplitude cannot be detected. Therefore, there is a problem that the reproduction signal is temporarily lost when the device vibrates.

In view of the above points, it is an object of the present invention to provide a digital signal reproducing apparatus capable of reproducing a continuous signal without missing a reproduced signal even if the apparatus vibrates.

[0010]

The above-mentioned problems can be solved by the following constitution.

That is, a drive unit for driving a recording medium at an arbitrarily variable drive speed, a signal detection unit for detecting a digital signal recorded on the recording medium, and a digital signal detected by the signal detection unit for the recording medium. The playback unit that performs playback processing at a processing speed that is variable according to the drive speed of the, a buffer memory that stores the playback digital signal from the playback unit, a vibration detection unit that detects the vibration of the recording medium, and a playback digital signal buffer Once the fixed amount is stored in the memory, the buffer memory is controlled to output the reproduced digital signal at a constant output transfer rate according to the normal driving speed of the recording medium, and at the same time, the driving unit, the signal detection unit and the reproducing unit are controlled. A control unit is provided, and when the reproduction digital signal is stored in the buffer memory by the control unit in a certain amount, the control unit drives the recording medium in a normal drive mode. The digital signal stored in the buffer memory while controlling the drive unit to drive at the speed and moving the signal detection unit to the position before the vibration of the recording medium is detected according to the vibration detection signal from the vibration detection unit. The drive unit, the signal detection unit and the reproduction unit are controlled so as to reproduce the drive speed of the recording medium as a drive speed higher than the normal drive speed until the above-mentioned constant amount.

[0012]

According to the above construction, once the recording medium is driven at an arbitrary driving speed and the reproduced digital signal is once stored in the buffer memory in a certain amount, the recording medium is driven at the normal driving speed to move from the buffer memory. The digital signal is output at an output transfer rate according to the normal drive speed, and even if the recording medium vibrates, the digital signal is output from the buffer memory at an output transfer rate according to the normal drive speed thereafter. The signal detector is controlled to move to a position before the recording medium vibrates so that the recording medium is driven at a driving speed higher than the normal driving speed, and acts to store a certain amount of digital signals in the buffer memory. ..

[0013]

1 is a block diagram of a CD player according to an embodiment of the present invention. In the figure, the same components as those in FIG. 5 are designated by the same reference numerals.

The drive unit 12 and the signal processor 15 shown in FIG. 1 have basically the same configuration and function as the drive unit 2 or the signal processor 5 shown in FIG. Is added to the function of varying the drive speed of the optical disk 10 or the processing speed of the reproduction signal by the signal from the.

As a result, the spindle motor is rotationally driven at, for example, twice the normal rotational speed, and the optical disk 10 (recording medium) is selectively driven in the standard reproduction mode or the double speed reproduction mode.

RF amplifier circuit 3 and signal processor 15
The digital signal detected from the optical disc 10 which is rotationally driven in the double speed reproduction mode is R
After being amplified by the F amplifier circuit 3, the signal processor 15
Is reproduced in the double speed reproduction mode by the optical disc 10
It is output at a speed according to the driving speed of.

The servo circuit 14 which is the vibration detecting section is also constructed so that the processing speed is varied by the signal from the microprocessor 11, and the tracking error signal, the focus error signal, the spindle from the signal of the double speed reproduction mode from the RF amplifier circuit 3. It generates signals such as motor drive signals.

Further, the servo circuit 14 detects, for example, an AC component of the tracking error signal or the focus error signal, and when the device vibrates due to an external cause and the optical disc 10 vibrates with respect to the optical pickup 13 (signal detecting means), these components are detected. The vibration detection signal DEsh is generated by detecting that the AC component of the signal becomes approximately 0.

Alternatively, when the DC level of the spindle motor drive signal changes, the vibration detection signal DE
It is also possible to generate sh.

By the way, the input memory 16, the buffer memory 17, and the control unit 8 including the microprocessor 11, the control circuit 18, and the address designating circuit 19 constitute a main part of this embodiment.

To briefly describe these, the input memory 16 captures the digital signal from the signal processor 15 at an input transfer rate according to the processing speed of the signal processor 15, and when it captures the digital signal to its full capacity, the same as the input transfer rate. Is controlled by the control circuit 18 to output to the buffer memory 17 at the output transfer rate of.

The buffer memory 17 uses the input memory 1 at the same input transfer rate as the output transfer rate of the input memory 16.
The digital signal from No. 6 is taken in and output at a constant output transfer rate according to the normal (standard reproduction mode) drive speed of the optical disk 10.

The addresses of the memories 16 and 17 are determined by the control circuit 18 and the address designating circuit 19. The control circuit 18 includes an input memory 16, a buffer memory 17,
By communicating with the address designating circuit 19, control is performed so that digital signals are sequentially stored in the vacant addresses of the memories 16 and 17 that are generated and output.

FIG. 2 is a timing chart of an embodiment of the present invention, and FIGS. 3 and 4 are flow charts of an embodiment of the present invention. The operation of the main part of this embodiment will be described below with reference to FIGS.

In FIG. 2, (A) is the input data Din of the input memory 16, (B) is the input clock CKin for controlling the input transfer rate to the input memory 16, (C) is the output data Dout of the buffer memory 17, (D) is an output clock C for controlling the output transfer rate to the buffer memory 17.
Kout and (E) represent the vibration detection signal DEsh generated by the servo circuit 14, respectively.

In FIG. 3, first, the apparatus is activated to seek to a desired track (step 21), and the double speed reproduction mode is entered at time t ₀ in FIG. 2 (step 2).
2). At this time, the control circuit 18 instructs the address to the input memory 16 (step 23), and the signal processor 15
To the address of the input memory 16 designated by the input clock CKin (frequency at this time fin = 2.4224MH
Input data Din is 1 in synchronization with the rising edge of z)
It is stored byte by byte (step 24).

Further, an address is designated to the buffer memory 17 (step 25), and the data stored in the input memory 16 is controlled to be transferred byte by byte to the designated address of the buffer memory 17 (step 2).
6).

Next, for example, in the control circuit 18, CK
In is counted, the counting result is notified to the microprocessor 11, and the microprocessor 11 determines whether or not the buffer memory 17 is full (step 27). If the buffer memory 17 does not have the full capacity, the processes of steps 23 to 26 are repeatedly executed, and the process of step 27 is executed again.

When it is determined that the buffer memory 17 is full at time t ₁ , the input clock CK
The frequency of in is set to 2 fin. At the same time, the microprocessor 11 also outputs a signal instructing the standard reproduction mode to the drive unit 12, the servo circuit 14, and the signal processor 15.

The supply of the output clock CKout (fout = 1.2112 MHz) to the buffer memory 17 is started. As a result, in synchronization with the rising edge of the output clock CKout, output of the output data Dout from the buffer memory 17 to the D / A converter 6 is started in the standard reproduction mode for each byte (steps 28 and 29).

In this way, when the apparatus is started up and driven in the double speed reproduction mode to fill the buffer memory 17 to its full capacity, it shifts to the standard reproduction mode and the buffer memory 17 is operated.
From the input memory 16 with a delay of a predetermined clock
The output data Dout is output for each byte in synchronism with the loading into the memory.

Next, in FIG. 4, it is judged whether the servo circuit 14 detects the vibration of the apparatus (step 38). If the vibration is not detected, the standard reproduction mode is continued (step 3).
9), while taking in Din at the input transfer rate according to the normal drive speed of the optical disc 10, similarly D / the continuous data Dout at the output transfer rate according to the normal drive speed
The output continues to the A converter 6.

When the apparatus vibrates at time t ₂ in FIG. 2, the input data Din is no longer supplied from the signal processor 15. At the same time, the servo circuit 14 detects the vibration of the device and outputs a high level vibration detection signal DEsh to the microprocessor 11.

At this time, the data accumulated and stored at the full capacity of the buffer memory 17 is continuously output to the D / A converter 6 in the standard reproduction mode as shown in FIG. 2C (step 40). The optical pickup 13 is sought to the address immediately before the vibration is detected (step 4).
1).

Optical pickup 1 from time t ₂ to t ₃
As shown in FIG. 2 (A), Din is not supplied to the input memory 16 while seeking 3; therefore, an empty address is generated in the input memory 16 and the buffer memory 17.

Therefore, after the seek to the target track is completed, after time t ₃ , the frequency of CKin is set to 2.4224 MHz in step 42 so that the input transfer rate to the input memory 16 is faster than the output transfer rate of the buffer memory 17 and the double speed is set. Din is taken into the input memory 16 in the reproduction mode.

Thereafter, by repeating the processing of steps 43 to 47 similar to the processing of steps 23 to 27 (FIG. 3), the input transfer rate to the input memory 16 and the output transfer rate of the buffer memory 17 are set. Data is gradually accumulated in the vacant address according to the difference. These processes are repeatedly executed until time t ₄ when the buffer memory 17 becomes full.

When it is determined that the buffer memory 17 has become full at time t ₄ (step 47),
Similar to step 29, the standard playback mode is entered, and the Din is set at the input transfer rate according to the normal drive speed of the optical disk 10.
While taking in the data, the continuous data Dout is similarly output at the output transfer rate according to the normal drive speed, and the D / A converter 6
Output to.

As described above, according to the present embodiment, even if the optical disk 10 vibrates with respect to the optical pickup 13 and the reproduction signal is interrupted at the output of the signal processor 15, the data stored in the buffer memory 17 can be stored in the optical disk. While continuously outputting to the D / A converter 6 at an output transfer rate according to the normal drive speed of the optical pickup 10, the optical pickup 13 is placed at a position before the optical disc 10 vibrates.
By reproducing in the double speed reproduction mode from the position where the vibration occurs and storing the reproduction data to the full capacity of the buffer memory 17, even if the device vibrates due to an external factor, the reproduction signal does not drop and continues. It has the excellent feature that it can reproduce the generated signal.

By the way, when a vibration is detected in the double speed reproduction mode, the optical pickup is further sought to the address before the vibration is detected, so that a continuous signal without loss can be obtained. it is conceivable that.

Further, an 8-12 bit conversion circuit is provided after the RF amplification circuit 3 to convert the reproduced RF signal into a signal subjected to digital waveform processing, and this digital signal is input to the input memory 16
It is conceivable that the same effect can be obtained by storing the data in the buffer memory 17 via the, and configuring the control unit 8 to perform the same control as above.

Further, in the above embodiment, the CD player which is the optical disk reproducing device has been described, but it is considered that the same effect can be obtained by applying the present invention to a digital tape recorder.

[0043]

As described above, according to the present invention, even if the recording medium vibrates with respect to the signal detecting portion, the digital signal stored in the buffer memory in a certain amount is output according to the normal driving speed of the recording medium. While continuously outputting at the transfer rate, move the signal detector to the position before the recording medium vibrates and drive at a drive speed faster than the normal drive speed, accumulate the reproduced digital signal and keep it constant in the buffer memory. Since it stores up to the amount, there is a feature that a continuous reproduction signal that is not lost even if the device vibrates can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention.

FIG. 2 is a timing chart of an example of the present invention.

FIG. 3 is a flow chart of an example of the present invention.

FIG. 4 is a flow chart of an example of the present invention.

FIG. 5 is a block diagram of an example of a conventional digital signal reproducing device.

[Explanation of symbols]

 2 and 12 drive part 3 RF amplification circuit 8 control part 9 reproduction part 10 optical disk (recording medium) 11 microprocessor 13 optical pickup (signal detection part) 14 servo circuit (vibration detection part) 15 signal processing processor 16 input memory 17 buffer memory 18 control circuit 19 address designating circuit

Claims (1)

[Claims] 1. A drive unit for driving a recording medium at an arbitrarily variable drive speed, a signal detection unit for detecting a digital signal recorded on the recording medium, and a digital signal detected by the signal detection unit. A reproducing unit that performs a reproducing process at a processing speed that is variable according to the driving speed of the recording medium, a buffer memory that stores a reproduced digital signal from the reproducing unit, and a vibration detecting unit that detects vibration of the recording medium, After the reproduction digital signal is once stored in the buffer memory in a fixed amount, the buffer memory is controlled so as to output the reproduction digital signal at a constant output transfer rate according to the normal drive speed of the recording medium, and The control unit controls the drive unit, the signal detection unit, and the reproduction unit, and stores a predetermined amount of the reproduction digital signal in the buffer memory. While the recording medium is being driven, the drive unit is controlled to drive the recording medium at the normal drive speed, and at the position before the vibration of the recording medium is detected in accordance with the vibration detection signal from the vibration detection unit. The drive unit, moving the signal detection unit, and reproducing the drive speed of the recording medium as a drive speed higher than the normal drive speed until the digital signal stored in the buffer memory reaches the constant amount. A digital signal reproducing apparatus characterized by being configured to control a signal detecting section and the reproducing section.